From d96038e0fa00f42a5d6711884bef0a725cdc70bb Mon Sep 17 00:00:00 2001 From: Viresh Kumar Date: Tue, 30 Apr 2013 14:32:18 +0000 Subject: [PATCH] cpufreq: Issue CPUFREQ_GOV_POLICY_EXIT notifier before dropping policy refcount We must call __cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT) before calling cpufreq_cpu_put(data), so that policy kobject have valid fields. Otherwise, removing last online cpu of policy->cpus causes this crash for ondemand/conservative governor. [] (sysfs_find_dirent+0xe/0xa8) from [] (sysfs_get_dirent+0x21/0x58) [] (sysfs_get_dirent+0x21/0x58) from [] (sysfs_remove_group+0x85/0xbc) [] (sysfs_remove_group+0x85/0xbc) from [] (cpufreq_governor_dbs+0x369/0x4a0) [] (cpufreq_governor_dbs+0x369/0x4a0) from [] (__cpufreq_governor+0x2b/0x8c) [] (__cpufreq_governor+0x2b/0x8c) from [] (__cpufreq_remove_dev.isra.12+0x15b/0x250) [] (__cpufreq_remove_dev.isra.12+0x15b/0x250) from [] (cpufreq_cpu_callback+0x2f/0x3c) [] (cpufreq_cpu_callback+0x2f/0x3c) from [] (notifier_call_chain+0x45/0x54) [] (notifier_call_chain+0x45/0x54) from [] (__cpu_notify+0x1d/0x34) [] (__cpu_notify+0x1d/0x34) from [] (_cpu_down+0x63/0x1ac) [] (_cpu_down+0x63/0x1ac) from [] (cpu_down+0x1b/0x30) [] (cpu_down+0x1b/0x30) from [] (store_online+0x27/0x54) [] (store_online+0x27/0x54) from [] (dev_attr_store+0x11/0x18) [] (dev_attr_store+0x11/0x18) from [] (sysfs_write_file+0xed/0x114) [] (sysfs_write_file+0xed/0x114) from [] (vfs_write+0x65/0xd8) [] (vfs_write+0x65/0xd8) from [] (sys_write+0x2f/0x50) [] (sys_write+0x2f/0x50) from [] (ret_fast_syscall+0x1/0x52) Of course this only impacted drivers which have have_governor_per_policy set to true. i.e. big LITTLE cpufreq driver. Signed-off-by: Viresh Kumar Signed-off-by: Rafael J. Wysocki --- drivers/cpufreq/cpufreq.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 1b8a48eaf90f..b7acfd153bf9 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -1075,14 +1075,14 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif __func__, cpu_dev->id, cpu); } + if ((cpus == 1) && (cpufreq_driver->target)) + __cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT); + pr_debug("%s: removing link, cpu: %d\n", __func__, cpu); cpufreq_cpu_put(data); /* If cpu is last user of policy, free policy */ if (cpus == 1) { - if (cpufreq_driver->target) - __cpufreq_governor(data, CPUFREQ_GOV_POLICY_EXIT); - lock_policy_rwsem_read(cpu); kobj = &data->kobj; cmp = &data->kobj_unregister; -- 2.30.2